Certain radiation curable coatings and films such as those formed from the acrylates, particularly propane trimethanol triacrylate, trimethacrylate, pentaerythritol triacrylate, and hexanediol diacylate or methacrylate, are in great demand because of their rapid curing properties.
Since acrylate compounds are not conducive to cationically induced radiation curing, they require more costly free radical systems which are oxygen inhibited unless effected in an inert atmosphere, generally under a blanket of nitrogen. Although formulation with a photoinitiator which undergoes bimolecular reaction with a hydrogen donor minimizes the inhibitory effect of air, this benefit is realized at the expense of a greatly reduced cure rate. Also, it is found that polymerization or curing in free radical systems ceases almost immediately upon removal from the source of radiation; thus, the cured product likely contains significant amounts of unpolymerized components. Accordingly, it is an aim of research to develop a compound having the beneficial properties of acrylates but which is amenable to radiation curing at a rapid rate by cationically induced polymerization which is not oxygen inhibited and which permits continued polymerization after removal from the source of radiation exposure.
Finally, it is noted that the unsubstituted acrylates are sensitizers and skin irritants as well as being carcinogenic, so that specialized safety precautions must be taken to protect operators from exposure. Although alkoxylation has lessened irritancy of the acrylates, their carcinogenic properties are not reduced.
Accordingly, it is an object of this invention to overcome or minimize the above described deficiencies and to provide oligomeric materials capable of altering the curing characteristics of vinyl ether, epoxy and acrylate monomers and polymers.
Another object of this invention is to provide an economical and commercially feasible process for synthesizing radiation curable epoxy vinyl ethers.
Still another object of this invention is to provide compounds which possess good photoresist properties.
Another object is to provide a homopolymerizable compound readily curable by cationic radiation to a hard coating or film which is resistant to chemical attack.
These and other objects of the invention will become apparent from the following description and disclosure.